1. Field of the Invention
The present invention relates to a printing system, and more particularly, to a print media handling system and associated method.
2. Description of the Related Art
In a typical ink jet printer, print media is directed through a print cycle which includes picking a media sheet from an input tray, transporting the media sheet through a printing zone for printing, and then transporting the printed sheet through an output port. Once the printed sheet exits the output port, the printed sheet is received by an output tray. Consecutive printed sheets are piled one on top of another as successive sheets are printed to form an output stack. Since ink jet printers print with a liquid ink, and because sheets often are stacked immediately after printing, ink jet printers have in the past experienced some difficulty with smearing of ink upon contact of a previously printed sheet by an immediately subsequent printed sheet. This has been particularly apparent where ink drying time exceeds the time between the printing of consecutive sheets.
A variety of approaches have been used in attempting to deal with this problem. For example, some manufactures have attempted to eliminate ink smearing problems by decreasing ink drying time by employed quick-drying ink, or specially-coated paper, often resulting in poorer quality print. Also, some manufacturers have incorporated a drying lamp or heater in the printer near the printed media sheet, thus adding to the complexity of the printer, and consequently adding to the printer's price. Still other manufacturers have attempted to delay the delivery of printed sheets to the output tray so as to provide the previously printed sheet with adequate drying time.
One such an attempt to delay the delivery of printed sheets to the output tray so as to provide the previously printed sheet with adequate drying time is to use a passive sheet media drop scheme, whereby a printed sheet exiting the printer's output port is guided along rails which temporarily support the sheet above the output tray. Upon completion of printing, the sheet drops under the effect of gravity into the output tray, thereby allowing the previously printed sheet sufficient time to dry during printing of the present sheet. One problem associated with such a passive system, however, is the inability to adapt its operation to various printing environments or when a large quantity of ink is deposited on the printed sheet.
One solution to the problems associated with such a passive system is to provide an active sheet media delivery mechanism, wherein a printed sheet is guided along a pair of movable rails which temporarily support the sheet above the printer's output tray while the previously printed sheet drys. Once printing is completed, the rails retract, often pivotally, allowing the sheet to fall to an output tray below. Although generally effective, active drop mechanisms generally have presented problems due to permitting the skewing of sheets in the output tray, and as a result, generally pose limitations on output tray capacity. In addition, such active sheet media delivery mechanisms are driven cyclically by the same drive which drives the paper feed, thereby limiting operating adaptability.